a) ( 5 / 12 + 1/6 + 3/8): 15/16
1) 5/12 + 1/6 + 3/8 = 10/24 +4/24 + 9/24 = 23/24
2) 23/24 : 15/16 = 23*16 / 24/15 = 46/45 = 1 1/15
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б) 5:1 1/4+7:2 1/3
1) 5: 1 1/4 = 5/1 : 5/4 = 5*4 / 1*5 = 4
2) 7 : 2 1/3 = 7/1 : 7/3 = 7*3 / 1*7 = 3
3) 4+3 = 7
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в) (6/21+1/7-5/14):(5/18-1/9+3/6)
1) 6/21+1/7-5/14 = 12/42 + 6/42 - 15/42 = 3/42 = 1/14
2) 5/18 - 1/9 + 3/6 = 5/18 - 2/18 + 9/18 = 12/18 = 2/3
3) 1/14 : 2/3 = 1*3/14*2=3/28
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г) 77:11/12-19:2 3/8
1) 77 : 11/12 = 77*12 / 1*11 = 84
2) 19 : 2 3/8 = 19/1 : 19/8 = 19*8 / 1*19 = 8
3) 84 - 8 = 76